The invention relates to a method for reading out error statistics data which are produced in duplicate processing units.
Accordingly, this concerns the reading out of error statistics data which arise in duplicated processing units operated in microsynchronous parallel operation for processing ATM information. In this arrangement, the processing units are connected to a switching matrix which may be duplicated. They output in each case, for generating the microsynchronous parallel operation, a synchronization signal identifying the corresponding processing phase if the received information to be processed is free of errors and, respectively, the results of the information processing to be sent out are free of errors, to the partner unit, to which synchronization signal the beginning of the processing phase of the latter unit is synchronized. If there is no synchronization signal from the partner unit, the processing unit concerned, however, stops information processing, that is to say rejects the received information even in the case of correct reception of information just as in the case of faulty information. This correspondingly applies to the transmitter direction. In this case, blank information is output even though a faultless information processing result is given.
The processing units are connected via a bus interface to a central control unit which compares information items reaching it with one another, among other things for monitoring the microsynchronous operation of the processing units.
In the case of the constellation described, different error situations can arise in the duplicated processing units so that the error statistics are also different without this having to interfere with the microsynchronous parallel operation.
If any error statistics data were being read out like ATM information directly via the abovementioned bus interface for the purpose of evaluation and thus also subjected to a comparison, it would be highly probable that an inequality and thus erroneously the loss of microsynchronism would be signalled.